Catalytic Dewaxing Process

ABSTRACT

In a catalytic dewaxing process, a catalyst comprising from 40 to 80 wt % of ZSM-48 having a silica to alumina molar ratio of less than 200:1 and from 0.3 to 1.5 wt % of a metal or metal compound from Groups 8 to 10 of the Periodic Table of the Elements is provided in a reaction zone. The catalyst is periodically contacted in the reaction zone under dewaxing conditions with a first hydrocarbon feedstock having a wax content of less than 50 wt % and with a second hydrocarbon feedstock having a wax content of 50 wt % or more.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application Ser.No. 61/284,835 filed Dec. 24, 2009, herein incorporated by reference inits entirety.

FIELD

The present disclosure relates to a process for catalytically dewaxingfeeds having a variety of wax contents.

BACKGROUND

Waxy feedstocks may be used to prepare basestocks having a highviscosity index (VI). However, in order to obtain a basestock having thelow temperature properties suitable for most uses, it is usuallynecessary to dewax the feedstock. Dewaxing may be accomplished by meansof a solvent or catalytically. Solvent dewaxing is a physical processwhereby waxes are removed by contacting with a solvent, such as methylethyl ketone, followed by chilling to crystallize the wax and filtrationto remove the wax. Catalytic dewaxing involves chemically converting theless desirable molecules to produce a basestock with more favorable lowtemperature properties. Long chain normal paraffins and slightlybranched paraffins readily solidify and thus result in generallyunfavorable low temperature properties. Catalytic dewaxing is a processfor converting these long chain normal paraffins and slightly branchedparaffins to improve the low temperature properties of the feed.

Catalytic dewaxing may be accomplished using catalysts that functionprimarily by cracking waxes to lower boiling products, or by catalyststhat primarily isomerize waxes to more highly branched products.Catalysts that dewax by cracking decrease the yield of lubricating oilswhile increasing the yield of lower boiling distillates. Catalysts thatisomerize do not normally result in significant boiling pointconversion. Catalysts that dewax primarily by cracking are exemplifiedby the zeolites ZSM-5, ZSM-11, ZSM-12, and offretite. Catalysts thatdewax primarily by isomerization are exemplified by the zeolites ZSM-22,ZSM-23, SSZ-32, ZSM-35, and ZSM-48.

In many refineries it is necessary to be able to dewax feeds having verylarge differences in wax content varying from, for example, a slack waxcontaining of the order of 90 wt % wax to a hydrocrackate containing 20wt % or less wax. In addition, despite the fact that zeolite dewaxingcatalysts are generally susceptible to poisoning by sulfur and nitrogenimpurities, it is also often necessary to handle feeds with a wide rangeof impurity levels.

Currently, the solution adopted by most refineries to deal with theproblem of varying wax content is to employ two different dewaxingtrains, each having a different dewaxing catalyst. One dewaxing train isthen used for low wax content feeds while the other is used for high waxcontent feeds. Although this is a costly solution, the limited activityof current dewaxing catalysts makes it difficult to design a singleplant that can handle all types of feed and still provide an acceptablyhigh throughput in the case of high wax feeds.

United States Published Patent Application No. 2007/0131581 disclosesZSM-48 having a silica to alumina molar ratio of 110 or less that isfree of non-ZSM-48 seed crystals and free of ZSM-50. The low silicaZSM-48 is shown to have improved activity in the dewaxing of slack wax.

According to the present disclosure, it has now been found that, byusing a particular catalyst system comprising a low silica/alumina ratioZSM-48, it is possible to use a single reactor operating in blocked modeto dewax both low and high wax feeds. The catalyst contains a low levelof hydrogenation metal and, even using high wax feeds, is sufficientlyactive to allow the dewaxing to be effected at commercially acceptablethroughput rates and at temperatures which minimize the undesirable drygas (C₄) make. The catalyst is also able to process feeds containinghigher levels of nitrogen and sulfur than a lower activity catalystcould handle.

SUMMARY

In one aspect, the disclosure resides in a catalytic dewaxing processcomprising:

(a) providing in a reaction zone a catalyst comprising from 40 to 80 wt% of ZSM-48 having a silica to alumina molar ratio of less than 200:1and from 0.3 to 1.5 wt % of a metal or metal compound from Groups 8 to10 of the Periodic Table of the Elements; and

(b) periodically contacting said catalyst in said reaction zone underdewaxing conditions with a first hydrocarbon feedstock having a waxcontent of less than 50 wt % and with a second hydrocarbon feedstockhaving a wax content of 50 wt % or more.

Conveniently, the catalyst comprises from 50 to 70 wt % of ZSM-48 havinga silica to alumina molar ratio of less than 200:1. In one embodiment,the ZSM-48 has a silica to alumina molar ratio of 100:1 or less.

Conveniently, the catalyst comprises from 0.3 to 0.8 wt % of a metal ormetal compound from Groups 8 to 10 of the Periodic Table of theElements, especially platinum.

Conveniently, the catalyst further comprises an inorganic oxide binder,such as silica, a silicate, or an aluminosilicate.

Conveniently, said dewaxing conditions include a temperature of 365° C.or less, such as from 290° C. to 365° C., and a liquid hourly spacevelocity on the hydrocarbon feed of at least 0.4 hr⁻¹, such as from 0.95to 3 hr⁻¹.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph comparing the average reaction temperature required toachieve different final pour points with high and low sulfurhydrotreated slack wax feeds using the dewaxing process of Example 3.

FIG. 2 is a graph comparing the 370° C.+ conversion required to achievedifferent final pour points with high and low sulfur feeds hydrotreatedslack wax feeds using the dewaxing process of Example 3.

FIG. 3 is a graph comparing the average reaction temperature required toachieve different final pour points with different feeds using thedewaxing catalyst of Example 1 and using a similar process but with ahigher silica to alumina ZSM-48 catalyst.

FIG. 4 is a graph comparing the 370° C.+ conversion required to achievedifferent final pour points with different feeds using the dewaxingcatalyst of Example 1 and using a similar process but with a highersilica to alumina ZSM-48 catalyst.

DETAILED DESCRIPTION

All numerical values within the detailed description and the claimsherein are modified by “about” or “approximately” the indicated value,and take into account experimental error and variations that would beexpected by a person having ordinary skill in the art.

Described herein is a process for dewaxing hydrocarbon feedstocks thatcontain widely varying levels of wax, for example from slack waxescontaining in excess of 90 wt % wax to a hydrocrackate containing lessthan 20 wt % wax, using a single catalyst in a single reactor in blockedoperation. In the present context, the term “blocked operation” meansthat, in dewaxing a first hydrocarbon feedstock having a wax content ofless than 50 wt % and a second hydrocarbon feedstock having a waxcontent of 50 wt % or more, the first feedstock would, for example, becontacted with the catalyst under dewaxing conditions for a certainperiod of time. The supply of the first feedstock to the reactor wouldthen be terminated or blocked, and the second feedstock would besupplied to the reactor without change-out of the catalyst but normallywith the dewaxing conditions being changed to deal with the higher waxcontent of the feed.

The present process employs a dewaxing catalyst comprising from 40 to 80wt %, such as from 50 to 70 wt %, of ZSM-48 zeolite having a silica toalumina molar ratio of less than 200:1, typically 100:1 or less, andfrom 0.3 to 1.5 wt %, such as from 0.3 to 0.8 wt %, of a hydrogenationmetal or metal compound from Groups 8 to 10 of the Periodic Table of theElements. Generally, the metal or metal compound from Groups 8 to 10 isplatinum or a compound thereof and is incorporated in the catalyst byimpregnation or ion exchange.

ZSM-48 is a zeolite having 10-ring unidirectional pores. ZSM-48, itsX-ray diffraction pattern and a method for its preparation are describedin each of U.S. Pat. Nos. 4,375,573, 4,397,827, 4,448,675 and 4,423,021.However, as conventionally synthesized, ZSM-48 has a silica/aluminamolar ratio in excess of 200:1.

The low silica/alumina ZSM-48 employed in the present process can beprepared by crystallizing a reaction mixture comprising silica, alumina,base, water and a directing agent (R) comprising a hexamethonium(N,N,N,N′,N′,N′-hexamethyl-1,6-hexanediammonium) salt, particularlyhexamethonium dichloride or dihydroxide. Typically, the reaction mixturehas the following composition.

SiO₂:Al₂O₃  70 to 110 H₂O:SiO₂   1 to 500 OH ⁻ :SiO₂  0.1 to 0.3,preferably 0.14 to 0.18 R:SiO₂=  0.01-0.05, preferably 0.015 to 0.025

The crystallization is generally conducted by stirring the reactionmixture at a temperature of 100 to 250° C. and produces ZSM-48 crystalshaving a silica:alumina molar ratio of 70 to 110 and a crystal size inthe range of 0.01 to 1 μm. More information on this process forproducing low silica/alumina ZSM-48 can be found in U.S. PublishedPatent Application No. 2007/0131581, the entire contents of which areincorporated herein by reference.

In addition to the ZSM-48 and hydrogenation metal, the catalyst employedin the present process typically also contains from 20 to 60 wt % of abinder or matrix material. Binders are attrition resistant and resistantto the temperatures experienced by the catalyst in use. Binders may becatalytically active or inactive and include other zeolites, otherinorganic materials such as clays and metal oxides, such as alumina,titania, silica and silica-alumina. Clays may be kaolin, bentonite andmontmorillonite and are commercially available. Other suitable porousmatrix materials in addition to silica-aluminas include other binarymaterials such as silica-magnesia, silica-thoria, silica-zirconia,silica-beryllia and silica-titania as well as ternary materials such assilica-alumina-magnesia, silica-alumina-thoria andsilica-alumina-zirconia.

The present process can be employed in the isomerization dewaxing of awide variety of lube oil feedstocks. Such feedstocks are generallywax-containing feeds that boil in the lubricating oil range, typicallyhaving a 10% distillation point greater than 650° F. (343° C.), measuredby ASTM D 86 or ASTM D2887. Such feeds may be derived from a number ofsources such as oils derived from solvent refining processes such asraffinates, partially solvent dewaxed oils, deasphalted oils,distillates, hydrocracker bottoms, vacuum gas oils, coker gas oils,slack waxes, foots oils and the like, and Fischer-Tropsch waxes.Preferred feeds are slack waxes and Fischer-Tropsch waxes. Slack waxesare typically derived from hydrocarbon feeds by solvent or propanedewaxing. Slack waxes contain some residual oil and are typicallydeoiled. Foots oils are derived from deoiled slack waxes.Fischer-Tropsch waxes are prepared by the Fischer-Tropsch syntheticprocess.

The feedstocks employed in the present process may have high contents ofnitrogen and/or sulfur contaminants. For example, feeds having anitrogen content of up to 80 ppm, even up to 150 ppm, and/or a sulfurcontent of up to 250 ppm, even up 1000 ppm, can be processed in thepresent process. Sulfur and nitrogen contents may be measured bystandard ASTM methods D2622 and D4629, respectively.

Suitable conditions for the present dewaxing process includetemperatures of up to 426° C., preferably 365° C. or less, morepreferably 290° C. to 365° C., pressures of from 791 to 20786 kPa (100to 3000 psig), preferably 1480 to 17339 kPa (200 to 2500 psig), liquidhourly space velocities of from 0.1 to 10 hr⁻¹, preferably at least 0.4hr⁻¹, more preferably from 0.95 to 3 hr⁻¹, and hydrogen treat gas ratesfrom 45 to 1780 m³/m³ (250 to 10000 scf/B), preferably 89 to 890 m³/m³(500 to 5000 scf/B).

The feedstocks used in the present process may be hydrotreated prior todewaxing. Suitable hydrotreating catalysts contain Group 6 metals, Group8-10 metals, and mixtures thereof. Examples of suitable metals includenickel, tungsten, molybdenum, cobalt and mixtures thereof. These metalsare typically present as oxides or sulfides on refractory metal oxidesupports. The mixture of metals may also be present as bulk metalcatalysts wherein the amount of metal is 30 wt % or greater, based oncatalyst. Suitable metal oxide supports include oxides such as silica,alumina, silica-aluminas or titania, preferably alumina. Preferredaluminas are porous aluminas such as gamma or eta. The amount of metal,either individually or in mixtures, ranges from 0.5 to 35 wt %, based onthe catalyst.

Suitable hydrotreating conditions include temperatures of up to 426° C.,such as from 150 to 400° C., for example from 200 to 350° C., a hydrogenpartial pressure of from 1480 to 20786 kPa (200 to 3000 psig), such asfrom 2859 to 13891 kPa (400 to 2000 psig), a space velocity of from 0.1to 10 hr⁴, such as from 0.1 to 5 hr⁻¹, and a hydrogen to feed ratio offrom 89 to 1780 m³/m³ (500 to 10000 scf/B), preferably 178 to 890 m³/m³.

The disclosure will now be more particularly described with reference tothe following Examples and the accompanying drawings.

EXAMPLES Example 1

The dewaxing catalyst employed in this Example comprised of 65 wt % ofZSM-48 having a silica to alumina molar ratio of 90/1 and 35 wt %alumina in the form of a 1.5 mm diameter by 3.25 mm length quadrulobeextrudate. This extrudate was steamed for 3 hours at 482° C. prior toimpregnation with 0.3 wt % platinum (as tetraammine platinum nitratesalt). The catalyst was loaded into a vertical downflow reactor beneatha top bed of a hydrotreating catalyst comprising 15 wt % Pt/Pd onalumina.

The above catalyst combination was used to consecutively hydrotreat andhydroisomerize four different feeds, a light neutral (LN) and a heavyneutral (HN) slack wax and an LN and an HN hydrocrackate having theproperties listed in Table 1. The process was conducted at a liquidhourly space velocity (LHSV) 1 hr⁻¹, a hydrogen circulation rate of 419Nm³/m³, a pressure of 107 kg/cm² and an average reaction temperatureadjusted to produce lube fractions having substantially the same pourpoint. The results are summarized in Table 1.

TABLE 1 Feed LN slack HN slack LN HN wax wax Hydrocrackate HydrocrackateDensity ASTM-287, gm/cc 0.811 0.820 0.839 0.845 Wax Yield D3235, % 94 8720 20 Sulfur D2622, ppm 5 5 10 10 Nitrogen, ppm 1 1 1 1Hydroisomerization Conditions Temp., ° C. 351 346 316 315 370° C.+conversion, % 43 32.5 7.2 6.8 Heavy Lube (400+° C.) Properties PourPoint D5950, ° C. −24 −18 −18 −15 VI 141.7 142.8 131 131.7 Yield, wt %38.1 54.6 70.5 82.8 Noack D5800, wt % (est.) 15 4.3 15 6.5 Light Lube(300-400° C.) Properties Pour Point D5950, ° C. −34 −33 −28 −28 VI 125.7117.8 119 111 Yield, wt % 26.3 13.6 6.8 5.8 Total lube yield, wt % 64.468.2 77.3 88.6 Dry gas, wt % 3.14 2.29 0.60 0.53

By comparing the required temperatures for reaction (hydroisomerization)versus wax content in Table 1, it can be seen that the light neutral(LN) slack wax required 0.47° C. reactor temperature increase per 1% waxin feed (calculated by dividing the 35° C. temperature increase requiredfor dewaxing the LN slack wax as compared with the LN Hydrocrackate bythe 74 wt % difference in wax content). This is an improvement over thetypical value of 0.65-1.0° C. per 1% wax in feed and results in loweroperating temperatures being required when processing higher waxcontaining feeds (See Wenlei Cao, “Production of High-QualityHydrogenated Base Oil Using Isomerization Dewaxing Technology”,Proceedings from China Refining Technology Conference, November 2005 inZhuhai, China pp 207-218 ISBN 7-80164-888-9). In this Example low gasmakes are also achieved some of which is due to catalyst type and somedue to low operating temperatures. Even higher wax contents up to 100%are possible, such as GTL type stocks.

Example 2

This Example is a hypothetical example using the dewaxing catalyst andprocess conditions of Example 1 to process a similar set of feeds buthaving higher levels of sulfur and nitrogen impurities. The operatingtemperatures required to achieve the same 370° C.+ conversion as inExample 1 were calculated and the results are shown in Table 2.

TABLE 2 Feed LN slack HN slack LN HN wax wax Hydrocrackate HydrocrackateDensity ASTM-287, g/cc 0.811 0.820 0.839 0.845 Wax Yield D3235, % 94 8720 20 Sulfur D2622, ppm 27 122 259 250 Nitrogen, ppm 3.5 5 80 80Hydroisomerization Conditions Temp., ° C. 365 364 364 363 370° C.+conversion, % 43 32.5 7.2 6.8

Table 2 shows that, depending on the wax content of the feed, highlevels of sulfur and nitrogen that can be tolerated at nominal 365° C.dewaxing temperature with the catalyst of Example 1. Note that theconversion levels are the same in Example 2 as Example 1 thus leading tosimilar lube yields and properties.

Example 3

In this Example, the dewaxing catalyst of Example 1 was used to dewaxtwo similar slack wax feeds that had undergone prior hydrotreatment witha conventional NiMo on alumina HDT catalyst under similar conditions asspecified in Table 3 but with the temperature adjusted to result inhydrotreated products with different sulfur levels.

TABLE 3 Feed A B HDT Conditions H2, circ., Nm³/m³ 168 168 Weight averagebed 220/230 230/240 temperature (Wabt) LHSV 1.0 1.0 H2 cons., Nm³/m³ 2020 Yields C1-C6 Nil Nil 265° C.− Nil Nil 265-343° C. 0.5 0.6 343-370° C.2.4 2.7 370° C.+ 97.3 96.9 Product Properties Sulfur, ppm 18 48Nitrogen, ppm 1 1 Specific Gravity 0.8140 0.8144 IBP, ASTM D2887 342 341 5% 379 378 50% 426 427 95% 466 466 Oil in wax D3235, % 8 9

The resultant hydrotrreated products were dewaxed to different pourpoints between −10 and −36° C. using the dewaxing catalyst specified inExample 1 and the results are summarized in FIGS. 1 and 2. The feedproperties for dewaxing are shown in Table 3 as “Product Properties”from the hydrotreating step. FIG. 1 shows that, although slightly highertemperatures (around 5° C.) were required to reached the desired pourpoint with the higher sulfur content feed, pour points as low as −36° C.could still be achieved at reaction temperatures below 365° C. FIG. 2shows that, in terms of conversion of 370° C.+ fraction, the impact ofthe higher sulfur content of feed B was a decreased lube yield of 6-10%.However, both of these results represent a significant improvement overresults reported for conventional dewaxing catalysts, where reactiontemperatures in excess of 365° C. and yield losses of 7-18% wererequired to achieve similar pour points. (See Wenlei Cao, “Production ofHigh-Quality Hydrogenated Base Oil Using Isomerization DewaxingTechnology”, Proceedings from China Refining Technology Conference,November 2005 in Zhuhai, China pp 207-218 ISBN 7-80164-888-9).

Example 4

In this Example, the impact of sulfur was determined directly by spikinga heavy hydrocrackate feed with a polysulfide, such as Sulfrzol to 450ppm dosage. The unspiked feed had the following analysis:

API 37.8 Sulfur D2622, ppm 20   IBP, D2887  560° C. 5%  698° C. 50  936°C. 90 1050° C.

As in Example 1, a dual catalyst was used comprising a top bed of ahydrotreating catalyst comprising 15 wt % Pt/Pd on alumina and a bottombed of a dewaxing catalyst. The dewaxing catalyst comprised 65 wt % ofZSM-48 having a silica to alumina molar ratio of 90/1 and 35 wt %alumina in the form of a 1.5 mm diameter by 3.25 mm length quadrulobeextrudate. The extrudate was steamed for 3 hours at 482° C. prior toimpregnation with 0.6 wt % platinum (as tetraammine platinum nitratesalt).

The feed was treated at a 421 Nm³/m³ hydrogen circulation rate, an LHSVof 1.33 hr⁻¹, a pressure of 1600 psig (11133 kPa) and at thetemperatures shown in Table 4. The results are also shown in Table 4 anddemonstrate that the high activity catalyst, by allowing dewaxing to beeffected at lower temperatures, permits higher sulfur content feeds tobe processed while maintaining reasonable lube yields.

TABLE 4 Feed Rx Temp, Pour Point 370° C.+ ° C. D5950, ° C. Yield, wt %No Sulfur 329 −25 88.5 450 ppm S spiked 329 −3  88.0 450 ppm S spiked337 −18 86.2

Example 5

Dewaxing of two similar feeds, Feed A: a medium pressure hydrocrackate(MPHC) and Feed B: a lube hydrocrackate (LHDC), were investigated inthis Example. The feeds had the properties shown in Table 5.

TABLE 5 Feed A B API 28.4 28.4 Nitrogen, ppm 6 3 Sulfur D2622, ppm 29 31IBP, ASTM D2887 508 705  5% 619 768 50% 787 929 90% 896 1047

The feeds were dewaxed using two different ZSM-48 catalysts. The firstcatalyst was the same dewaxing catalyst employed in Example 1. Thesecond catalyst comprised 65 wt % of ZSM-48 having a silica to aluminamolar ratio of 200/1 and 35 wt % alumina in the form of a 1.5 mmdiameter by 3.25 mm length quadrulobe extrudate. The extrudate wassteamed for 3 hours at 482° C. prior to impregnation with 0.6 wt %platinum (as tetraammine platinum nitrate salt). The feed was treated ata 421 Nm³/m³ hydrogen circulation rate, an LHSV of 1.33 hr⁻¹, a pressureof 2000 psig (13789 kPa). The results are shown in FIGS. 3 and 4 anddemonstrate that the low silica/alumina ratio catalyst of Example 1 at aPt content of only 0.3 wt % exhibits similar activity and selectivity(as measured by 370° C.+ conversion) to the higher silica/alumina ratiocatalyst with a Pt content of 0.6 wt %. This example teaches that thehigher zeolite activity can be compensated for by lowering the metalcontent.

Feed B used in Example 5 is similar to the feed used in Example 4.Processing conditions are also similar between the two examples,although there is a 400 psig difference in pressure. If one compares theno sulfur result in Example 4 which used a catalyst comprised of 90/1Si/Al2 crystal and 0.6 wt % Pt to the Feed B result processed with 0.3wt % Pt and 90/1 Si/Al₂ ratio, one can see that increasing the metalcontent from 0.3 wt % to 0.6 wt % increases the catalyst activity.Example 4 required only 329° C. to achieve a −25° C. pour point, whilethe catalyst from Example 5 with half the metal required approximately340° C. to achieve a similar pour point.

Applicants have attempted to disclose all forms and applications of thedisclosed subject matter that could be reasonably foreseen. However,there may be unforeseeable, insubstantial modifications that remain asequivalents. While the present disclosure has been described inconjunction with specific, exemplary forms thereof, it is evident thatmany alterations, modifications, and variations will be apparent tothose skilled in the art in light of the foregoing description withoutdeparting from the spirit or scope of the present disclosure.Accordingly, the present disclosure is intended to embrace all suchalterations, modifications, and variations of the above detaileddescription.

All patents, test procedures, and other documents cited herein,including priority documents, are fully incorporated by reference to theextent such disclosure is not inconsistent with this disclosure and forall jurisdictions in which such incorporation is permitted.

When numerical lower limits and numerical upper limits are listedherein, ranges from any lower limit to any upper limit are contemplated.

PCT Claims

1. A catalytic dewaxing process comprising:

-   -   (a) providing in a reaction zone a catalyst comprising from 40        to 80 wt % of ZSM-48 having a silica to alumina molar ratio of        less than 200:1 and from 0.3 to 1.5 wt % of a metal or metal        compound from Groups 8 to 10 of the Periodic Table of the        Elements; and    -   (b) periodically contacting said catalyst in said reaction zone        under dewaxing conditions with a first hydrocarbon feedstock        having a wax content of less than 50 wt % and with a second        hydrocarbon feedstock having a wax content of 50 wt % or more.

2. The process of claim 1, wherein the catalyst comprises from 50 to 70wt % of ZSM-48 having a silica to alumina molar ratio of less than200:1.

3. The process of claim 1 or claim 2, wherein the ZSM-48 has a silica toalumina molar ratio of 100:1 or less.

4. The process of any preceding claim, wherein the catalyst comprisesfrom 0.3 to 0.8 wt % of a metal or metal compound from Groups 8 to 10 ofthe Periodic Table of the Elements.

5. The process of any preceding claim, wherein said metal or metalcompound from Groups 8 to 10 of the Periodic Table of the Elementscomprises platinum.

6. The process of any preceding claim, wherein the catalyst furthercomprises an inorganic oxide binder.

7. The process of any preceding claim, wherein said dewaxing conditionsinclude a temperature of 365° C. or less.

8. The process of any preceding claim, wherein said dewaxing conditionsinclude a temperature of 290° C. to 365° C.

9. The process of any preceding claim, wherein said dewaxing conditionsinclude a liquid hourly space velocity on the hydrocarbon feed of atleast 0.4 hr⁻¹.

10. The process of any preceding claim, wherein said dewaxing conditionsinclude a liquid hourly space velocity on the hydrocarbon feed of 0.95to 2 hr⁻¹.

11. The process of any preceding claim, wherein one or both of saidfirst and second hydrocarbon feedstocks has a nitrogen content of up to150 ppm.

12. The process of any preceding claim, wherein one or both of saidfirst and second hydrocarbon feedstocks has a sulfur content of up to1000 ppm.

1. A catalytic dewaxing process comprising: (a) providing in a reactionzone a catalyst comprising from 40 to 80 wt % of ZSM-48 having a silicato alumina molar ratio of less than 200:1 and from 0.3 to 1.5 wt % of ametal or metal compound from Groups 8 to 10 of the Periodic Table of theElements; and (b) periodically contacting said catalyst in said reactionzone under dewaxing conditions with a first hydrocarbon feedstock havinga wax content of less than 50 wt % and with a second hydrocarbonfeedstock having a wax content of 50 wt % or more.
 2. The process ofclaim 1, wherein the catalyst comprises from 50 to 70 wt % of ZSM-48having a silica to alumina molar ratio of less than 200:1.
 3. Theprocess of claim 1, wherein the ZSM-48 has a silica to alumina molarratio of 100:1 or less.
 4. The process of claim 1, wherein the catalystcomprises from 0.3 to 0.8 wt % of a metal or metal compound from Groups8 to 10 of the Periodic Table of the Elements.
 5. The process of claim1, wherein said metal or metal compound from Groups 8 to 10 of thePeriodic Table of the Elements comprises platinum.
 6. The process ofclaim 1, wherein the catalyst further comprises an inorganic oxidebinder.
 7. The process of claim 1, wherein said dewaxing conditionsinclude a temperature of 365° C. or less.
 8. The process of claim 1,wherein said dewaxing conditions include a temperature of 290° C. to365° C.
 9. The process of claim 1, wherein said dewaxing conditionsinclude a liquid hourly space velocity on the hydrocarbon feed of atleast 0.4 hr⁻¹.
 10. The process of claim 1, wherein said dewaxingconditions include a liquid hourly space velocity on the hydrocarbonfeed of 0.95 to 2 hr⁻¹.
 11. The process of claim 1, wherein one or bothof said first and second hydrocarbon feedstocks has a nitrogen contentof up to 150 ppm.
 12. The process of claim 1, wherein one or both ofsaid first and second hydrocarbon feedstocks has a sulfur content of upto 1000 ppm.